Problem: $ { \left[\begin{array}{rr}{2} & {0} \\ {1} & {-2}\end{array}\right]-\left[\begin{array}{rr}{0} & {4} \\ {0} & {2}\end{array}\right] = {?} } $
Answer: To find the difference of two matrices, subtract the corresponding items between each matrix. ${\left[\begin{array}{rr}{2}-{0} & {0}-{4} \\ {1}-{0} & {-2}-{2}\end{array}\right]}$ Now, simplify: ${\left[\begin{array}{rr}{2} & {-4} \\ {1} & {-4}\end{array}\right]}$